1. Field of the Invention
The invention relates to an encoder apparatus for encoding a plurality of digital information signals into a transmission signal, to a method for encoding the plurality of digital information signals, and to a decoder apparatus for decoding the transmission signal so as to regenerate replicas of the plurality of digital information signals. An encoder apparatus in accordance with the opening paragraph is known from European Patent Application EP 678,226-A1, corresponding the U.S. Pat. No. 5,544,247, and U.S. patent application Ser. No. 08/651,016, filed May 21, 1996, which is Document (8) in the List of References at the end of this Description.
2. Description of the Related Art
Matrixing can be carried out when transmitting a first main signal component (the left hand signal component L of a stereo signal), a second main signal component (the right hand signal component R) and an auxiliary component (a central signal component C), such that a first composite signal component L.sub.0 is obtained which equals L+a.C and a second composite signal R.sub.0 is obtained which equals R+b.C, and where the signals L.sub.0, R.sub.0 and C are transmitted. Upon reception by a standard receiver not being provided with a corresponding dematrixing circuit, the signal components L.sub.0 and R.sub.0 are used for supplying via two stereo loudspeakers to a listener. The listener is thus able to perceive the C component transmitted as well, although he has a standard receiver.
Such matrixing schemes are discussed in J.A.E.S., Vol. 40, No. 5, May 1992, pp. 376-382, as well as in the publication `Matrixing of bitrate reduced audio signals` by W.R.Th. ten Kate et al, in Proc. of the ICASSP, 1992, March 23-26, San Francisco, Vol.2, pp. 11-205 to II-208, Documents (1a) and (1b) in the List of References, as well as Document (8).
Compression means for bit rate reducing a signal has been described in published European Patent Applications EP 457,390A1, corresponding to U.S. Pat. No. 5,367,608 (PHN 13.328) and 457,391A1 corresponding to U.S. Pat. No. 5,365,553 (PHN 13.329), Documents (7a) and (7b) respectively in the List of References. Further, reference is made to two ISO/IEC Standard Documents, Documents (9) and (10) in the List of References, referred to as MPEG-1 and MPEG-2 documents.